This application claims priority of Korea patent Application No. 2000-81824, filed on Dec. 26, 2000.
(a) Field of the Invention
The present invention relates to an automatic transmission of a vehicle, and more particularly, it relates to a control method for shifting from a reverse driving range to a forward driving range of an automatic transmission of a vehicle.
(b) Description of the Related Art
Generally, in an automatic transmission used for a vehicle, a control device performs control to realize automatic shifting into different speeds and shift ranges according to selection of a shift lever position, vehicle speed and the like. Conventionally, when a shift lever is positioned at a neutral range, a driver changes the shift lever to a reverse driving range and depresses an accelerator pedal to reverse the vehicle. Then, if the driver wants to proceed forward again, he would reduce the vehicle speed or stop the vehicle by using a brake system, change the shift lever from the reverse driving range to a forward driving range, depress the accelerator pedal, and drive the vehicle in the forward driving state.
A shift control of prior art performs shifting into a first gear or a second gear of the forward driving range on the basis of a vehicle speed of driving in the reverse driving range, when the shift lever is suddenly shifted into the forward driving range while driving in the reverse driving range.
However, in the case of an extremely low vehicle speed, a shifting mechanism (TCU) misrecognizes shifting from R (reverse driving range) xe2x86x92D (forward driving range) as shifting at a stop-state because a vehicle speed signal is not inputted, and performs a shifting into an unwanted gear.
For this reason, the shift control of prior art does not perform appropriate shifting along the entire vehicle speed range. More specifically, shift shock occurs if a vehicle is shifted into range D while driving in range R.
It is an objective of the present invention to provide a shift control method for shifting into a forward driving range while driving in a reverse driving range of an automatic transmission vehicle for reducing shift shock that occurs in changing a shift lever from a reverse driving range to a forward driving range, and to improve durability at the same time.
To achieve the above objective, the present invention provides a shift control method for shifting into a forward driving range while driving in a reverse driving range of an automatic transmission vehicle, wherein the method comprises detecting a shift lever position, an engine revolution speed, a throttle valve opening, and a speed of the vehicle, and performing a shift control operation for shifting into a first gear if the shift lever is changed from a reverse driving range to a forward driving range and the engine revolution state is an idling state, and if the detected throttle valve opening and the vehicle speed respectively are not more than predetermined values.